What motor do you have? The 3.4 you should only use dual electrode plugs (I prefer the NGK w/NGK wires). You should also reset the ECU and let it learn from stock. Just a thought.

I have the 3.4, and yes I will reset the ECU.
This dealership experience has been such a joke. I took my rig back today and the "certified" Toyota mech. told me that my engine was "TIRED" since I had installed a supercharger 90 thousand miles ago. He said he did a compresseion test and he got readings from 120 - 130 in the cylinders he checked. He told me that they should be reading 150 -160. I thought my compression was good for an engine with 165k on it.
He told me that I need to rebuild my engine (remember this is the same person who a day ago told me that my problem was my spark plugs) and that he could rebuild my engine in a week for around $7000.00. He would use "Venom" injectors instead of stock. When I asked him what size injectors they were, he did not know but once again said they were "Venom".
He kept talking about TRD this and TRD that, and when I asked him about the TRD 7th injector he had never heard about it! But he was sure quick to discount where I get my Runner info here on the fourm(s).
Anyways, I am going to continue to try and solve this problem myself with my limited knowledge but exceptional help from the true Toyota family here and at Yotatech.
I bought new spark plug wires today, new coil ignitions, and a throttle sensor, and am once again going to clean my throttle body. I may be shooting in the dark on some of these things, but I'm betting that something will fix my problem rather then rebuilding the engine.

I's justa has to ax....lol What dealership is this that you are dealing with? Majority of the dealerships around the Puget Sound are all to aware of this board and others...and are quickly becoming familiar with me. Nothing worse than a "certified" tech that is pushing aftermarket performance parts and doesnt have a freakin clue as to the volume they supply.
*Kinda fun being able to correct the service manager or head mechanic...Heartland Toyota has developed a taste for eating crow since meeting me. lol The dealership I trust the most and can rely on for a good OEM parts price is Bob Bridge Toyota in Renton. They got me the new tailgate glass for my 87' 4Runner for $30 cheaper than the used scratched POS the wrecking yards had.
~Darin <img src="/forums/images/graemlins/baby.gif" alt="" />

I SOLVED MY PROBLEM! It was the coil ignitions. When I took off the wire cap the metal nipple contact inside was completly green from water sitting in it. In fact all three of them were (from 4 wheeling in water that was up to the hood last year). Which means three of my cylinders were not firing correctly. I replaced with new ones along with new wires and the truck is running like a champ! I am seriously considering going back to Kirkland Toyota here in Wash State, and taking the "certified" mech. for a ride, and totally SMOKING the tires as I leave the dealership to take him for a test ride and ask whats wrong with my truck now?

I am going to run NGK plugs in mine. Anyone had any problems with those?

When you go back to Kirkland to give your "friend" a ride, bring him a picture of my motor, and tell him THAT is what a $7K rebuild will buy you on a 5VZ. What a joke, please be sure to rub his face in it <img src="/forums/images/graemlins/barf.gif" alt="" />

Congrads on fixing your problem BTW.

NW4Runner I actually copied pics and data from your web site to share with the master tech. This will be a fun visit.

I just pulled my Bosch plat.+4s out of my 91 3.0 and am going back to get stock NDs.Now where is that receipt so I can get my money back?The Boschs are guaranteed,right?

The Bosch are garunteed against Manufacturer's Defects only - not wear (even premature wear).

The first year I owned my Mitsu, I used Bosch Platinums. All I can say about 'em is they suck. That's my opinion about Bosch stuff in general.

NGKs or Densos (or even Champions for that matter) are made to be operated at specific temperature ranges. Going with a plug that's out of range will get you more misfires. I'm pretty sure the Bosch's aren't made for certain ranges - only more "flare" to entice an unsuspecting consumer (platinum, 2/4 prong, v-split, etc). I also don't like the idea of the tiny bit of electrode peeking through the ceramic. That's just me.

I just changed out some Bosch on my (x)girlfriend's Saturn and replaced them with NGKs. All of Bosch's had something wrong with them; one had the electrode falling out of it (scary). Saturn ran like a race car after that and a few other things (oil change, new ignition cables).

Ditto on the electrical engineering lesson: Electricity will follow the path of least resistance. Translated to Bosch 4-prongs that means that the electricity is going to choose one prong and stick with it (probably the closest in proximity with the least resistance).

Stick to stock or better (no gimmicks) and your motor will purrr. I'd recommend Magnecor plug wires if you can afford them. It's the last set of wires you'll ever own.

Trivia: the 4 ground plugs are for rotary engines. My roommate's 83 RX7 GSL came with them from the factory, and won't run on anything but.

FYI: our 2001 Tacoma with the 5VZ has a sticker on the timing belt cover that says use twin ground plugs only.